pharmacokinetics and pharmacodynamics

process of pharmacokinetics

absorption

• the process of moving their medications into systemic circulation

distribution

• medication passes to the body through the ECF and is distributed via the blood vessels and lymphatic system to the site of action in the body

metabolism

• the chemical change of the drug structure

  • most commonly occurs in the liver

excretions aka clearance

• the medication is removed form the body

  • most often occurs via the kidneys

therapeutic effect, half life, bioavailability

therapeutic effect: the client experiences the intended effect of the med without adverse effects or toxicity

half life: the amount of time required for the client’s plasma concentration to reach 50% of the initial dose of med

bioavailability: meds with lower bioavailability (oral meds) may result in decreased TE

factors influences pharmacokinetics processes

• absorption: oral, lower viability, slower

• distribution: instant

factors that influence metabolism

• genetics, age of client, hepatic and renal function, concurrent use of meds

first pass metabolism

• meds administered orally may go through first pass metabolism prior to distribution

• occurs primarily in the liver

• commonly lowers the availability of oral route meds

role of enzymes in med metabolism

• enzymes assist with the metabolism of meds

• the CYP450 family of enzymes in the liver metabolizes about 90% of meds

• enzymes can be induces or inhibited

excretion

• renal function

• pH or urine

• med interactions

pharmacodynamics

tolerance

• cell receptors become less responsive to the drug

withdrawal

• med withdrawal occurs when a regularly used substance is abruptly discontinued, resulting in a physical response in the body

receptor interactions of meds

agonists

• helper drugs, activate receptors on cells

  • ex: methadone, man made opioids prevent withdrawal

antagonists

• blocks, binds to receptors cause no effect or response

  • ex: naltrexone binds to receptor in the brain and causes no response

partial agonists

• weaker affect, bind and block receptor sites

  • ex: helps decrease craving of opioid

factors influencing receptor interactions

• concentration: intrinsic effect increase when concentration increases

• affinity: stronger effect when increases bond

• selectivity: lesser side effects less of the body

drug-drug interactions

impact on pharmacokinetics

• absorption: meds interacts that can be good/bad

• distribution: meds affects cardiac output, compete with each other

• metabolism: changes in blood flown in liver

• excretion: needs can affect blood flow in kidney which affect excretion through urine

adverse effects

defining adverse effects

• levels of severity

• action taken in response: ABCs

predicting adverse effects: multiple medications with the same effect, so put the client on the lowest dose for safety

minimizing adverse effects

monitoring to minimize adverse effects